The present invention relates to peptides derived from or based on bactericidal/permeability-increasing protein and therapeutic uses of such peptides.
Bactericidal/permeability-increasing protein (BPI) is a protein isolated from the granules of mammalian polymorphonuclear neutrophils (PMNs), which are blood cells essential in defending a mammal against invading microorganisms. Human BPI has been isolated from PMNs by acid extraction combined with either ion exchange chromatography (Elsbach, 1979, J. Biol. Chem. 254: 11000) or E. coli affinity chromatography (Weiss et al., 1987, Blood 69: 652), and has potent bactericidal activity against a broad spectrum of Gram-negative bacteria. The molecular weight of human BPI is approximately 55,000 daltons (55 kD). The complete amino acid sequence of human BPI, as well as the nucleotide sequence of DNA encoding BPI, have been elucidated by Gray et al., 1989, J. Biol. Chem. 264: 9505, incorporated herein by reference (see FIG. 1 in Gray et al.).
The bactericidal effect of BPI has been shown to be highly specific to sensitive Gram-negative species. The precise mechanism by which BPI kills Gram-negative bacteria is not yet known, but it is known that BPI must first attach to the surface of susceptible Gram-negative bacteria. This initial binding of BPI to the bacteria involves electrostatic interactions between BPI, which is a basic (i.e., positively charged) protein, and negatively charged sites on lipopolysaccharides LPS). LPS is also known as xe2x80x9cendotoxinxe2x80x9d because of the potent inflammatory response that it stimulates. LPS induces the release of mediators by host inflammatory cells which may ultimately result in irreversible endotoxic shock. BPI binds to Lipid A, the most toxic and most biologically active component of LPS.
BPI is also capable of neutralizing the endotoxic properties of LPS to which it binds. Because of its Gram-negative bactericidal properties and its ability to bind to and neutralize LPS, BPI can be utilized for the treatment of mammals suffering from diseases caused by Gram-negative bacteria, including bacteremia, endotoxemia, and sepsis. These dual properties of BPI make BPI particularly useful and advantageous for such therapeutic administration.
A proteolytic fragment corresponding to the amino-terminal portion of human BPI possesses the LPS binding and neutralizing activities and antibacterial activity of the naturally-derived 55 kD human holoprotein. In contrast to the amino-terminal portion, the carboxyl-terminal region of isolated human BPI displays only slightly detectable antibacterial activity (Ooi et al., 1991, J. Exp. Med. 174: 649). One BPI amino-terminal fragment, comprising approximately the first 199 amino acid residues of the human BPI holoprotein and referred to as xe2x80x9crBPI23xe2x80x9d (see Gazzano-Santoro et al., 1992, Infect. Immun. 60: 4754-4761) has been produced by recombinant means as a 23 kD protein. rBPI23 has been introduced into human clinical trials. Proinflammatory responses to endotoxin were significantly ameliorated when rBPI23 was co-administered with LPS.
Other endotoxin binding and neutralizing peptides are known in the art. One example is Limulus antilipopolysaccharide factor (LALF) from horseshoe crab amebocytes (Warren et al., 1992, Infect. Immunol. 60: 2506-2513). Another example is a cyclic, cationic lipopeptide from Bacilus polymyxa, termed Polymyxin B1. Polymyxin B1 is composed of six xcex1,xcex3-diaminobutyric acid residues, one D-phenylalanine, one leucine, one threonine and a 6-methyloctanoyl moiety (Morrison and Jacobs, 1976, Immunochem. 13: 813-818) and is also bactericidal. Polymyxin analogues lacking the fatty acid moiety are also known, which analogues retain LPS binding capacity but are without appreciable bactericidal activity (Danner et al., 1989, Antimicrob. Agents Chemother. 33: 1428-1434). Similar properties have also been found with synthetic cyclized polymyxin analogues (Rustici et al., 1993, Science 259: 361-365).
Known antibacterial peptides include cecropins and magainins. The cecropins are a family of antibacterial peptides found in the hemolymph of lepidopteran insects (Wade et al., 1990, Proc. Natl. Acad. Sci. USA 87: 4761-4765), and the magainins are a family of antibacterial peptides found in Xenopus skin and gastric mucosa (Zasloff et al., 1988, Proc. Natl. Acad. Sci. USA 85: 910-913). These peptides are linear and range from about 20 to about 40 amino acids in length. A less active mammalian cecropin has been reported from porcine intestinal mucosa, cecropin P1 (Boman et al., 1993, Infect. Immun. 61: 2978-2984). The cecropins are generally reported to be more potent than the magainins in bactericidal activity but appear to have less mammalian cell cytotoxicity. The cecropins and magainins are characterized by a continuous, amphipathic xcex1-helical region which is necessary for bactericidal activity. The most potent of the cecropins identified to date is cecropin A. The sequence of the first ten amino acids of the cecropin A has some homology with the BPI amino acid sequence 90-99. However, the other 27 amino acids of cecropin A are clearly necessary for its bactericidal activity and there is little homology with BPI for those 27 amino acids. The magainins have even less homology with the BPI sequence.
Of interest to the present application are the disclosures in PCT International Application PCT/US91/05758 relating to compositions comprising BPI and an anionic compound, which compositions are said to exhibit (1) no bactericidal activity and (2) endotoxin neutralizing activity. Anionic compounds are preferably a protein such as serum albumin but can also be a polysaccharide such as heparin. In addition, Weiss et al. (1975, J. Clin. Invest. 55: 33-42) disclose that heparin sulfate and LPS block expression of the permeability-increasing activity of BPI. However, neither reference discloses that BPI actually neutralizes the biologic activities of heparin. Heparin binding does not necessarily imply heparin neutralization. For example, a family of heparin binding growth factors (HBGF) requires heparin as a cofactor to elicit a biological response. Examples of HBGF""s include: fibroblast growth factors (FGF-1, FGF-2) and endothelial cell growth factors (ECGF-1, ECGF-2). Antithrombin III inhibition of clotting cascade proteases is another example of a heparin binding protein that requires heparin for activity and clearly does not neutralize heparin. Heparin binding proteins that do neutralize heparin (e.g., platelet factor IV, protamine, and thrombospondin) are generally inhibitory of the activities induced by heparin binding proteins that use heparin as a cofactor.
BPI (including amino-terminal fragments thereof) has a number of other important biological activities. For example, BPI has been shown to have heparin binding and heparin neutralization activities in copending and co-assigned parent U.S. patent application Ser. No. 08/030,644 filed Mar. 12, 1993 and continuation-in-part U.S. patent application Ser. No. 08/093,202, filed Jul. 15, 1993, the disclosures of which are incorporated by reference herein. These heparin binding and neutralization activities of BPI are significant due to the importance of current clinical uses of heparin. Heparin is commonly administered in doses of up to 400 U/kg during surgical procedures such as cardiopulmonary bypass, cardiac catherization and hemodialysis procedures in order to prevent blood coagulation during such procedures. When heparin is administered for anticoagulant effects during surgery, it is an important aspect of post-surgical therapy that the effects of heparin are promptly neutrazed so that normal coagulation function can be restored. Currently, protamine is used to neutraize heparin. Protamines are a class of simple, arginine-rich, strongly basic, low molecular weight proteins. Administered alone, protamines (usually in the form of protamine sulfate) have anti-coagulant effects. When administered in the presence of heparin, a stable complex is formed and the anticoagulant activity of both drugs is lost. However, significant hypotensive and anaphylactoid effects of protamine have limited its clinical utility. Thus, due to its heparin binding and neutralization activities, BPI has potential utility as a substitute for protamine in heparin neutralization in a clinical context without the deleterious side-effects which have limited the usefulness of the protaimies. The additional antibacterial and anti-endotoxin effects of BPI would also be useful and advantageous in post-surgical heparin neutralization compared with protamine.
Additionally, BPI is useful in inhibiting angiogenesis due in part to its heparin binding and neutralization activities. In adults, angiogenic growth factors are released as a result of vascular trauma (wound healing), immune stimuli (autoimmune disease), inflammatory mediators (prostaglandins) or from tumor cells. These factors induce proliferation of endothelial cells (which is necessary for angiogenesis) via a heparin-dependent receptor binding mechanism (see Yayon et al., 1991, Cell 64: 841-848). Angiogenesis is also associated with a number of other pathological conditions, including the growth, proliferation, and metastasis of various tumors; diabetic retinopathy, retrolental fibroplasia, neovascular glaucoma, psoriasis, angiofibromas, immune and non-immune inflammation including rheumatoid arthritis, capillary proliferation within atherosclerotic plaques, hemangiomas, endometriosis and Kaposi""s sarcoma. Thus, it would be desirable to inhibit angiogenesis in these and other instances, and the heparin binding and neutralization activities of BPI are useful to that end.
Several other heparin neutralizing proteins are also known to inhibit angiogenesis. For example, protamine is known to inhibit tumor-associated angiogenesis and subsequent tumor growth [see Folkman et al., 1992, Inflammation: Basic Principles and Clinical Correlates, 2d ed., (Galin et al., eds., Review Press, N.Y.), Ch. 40, pp. 821-839] A second heparin neutralizing protein, platelet factor IV, also inhibits angiogenesis (i.e., is angiostatic). Collagenase inhibitors are also known to inhibit angiogenesis (see Folkman et al., 1992, ibid.) Another known angiogenesis inhibitor, thrombospondin, binds to heparin with a repeating serine/tryptophan motif instead of a basic amino acid motif (see Guo et al., 1992, J. Biol. Chem. 267: 19349-19355).
Another utility of BPI involves pathological conditions associated with chronic inflammation, which is usually accompanied by angiogenesis. One example of a human disease related to chronic inflammation is arthritis, which involves inflammation of peripheral joints. In rheumatoid arthritis, the inflammation is immune-riven, while in reactive arthritis, inflammation is associated with infection of the synovial tissue with pyogenic bacteria or other infectious agents. Folkman et al., 1992, supra, have also noted that many types of arthritis progress from a stage dominated by an inflammatory infiltrate in the joint to a later stage in which a neovascular pannus invades the joint and begins to destroy cartilage. While it is unclear whether angiogenesis in arthritis is a causative component of the disease or an epiphenomenon, there is evidence that angiogenesis is necessary for the maintenance of synovitis in rheumatoid arthritis. One known angiogenesis inhibitor, AGM1470, has been shown to prevent the onset of arthritis and to inhibit established arthritis in collagen-induced arthritis models (Peacock et al., 1992, J. Exp. Med. 175: 1135-1138). While nonsteroidal anti-inflammatory drugs, corticosteroids and other therapies have provided treatment improvements for relief of arthritis, there remains a need in the art for more effective therapies for arthritis and other inflammatory diseases.
There continues to exist a need in the art for new products and methods for use as bactericidal agents and endotoxin neutralizing agents, and for heparin neutralization and inhibition of angiogenesis (normal or pathological). One avenue of investigation towards fulfilling this need is the determination of the functional domains of the BPI protein specifying each of these biological activities. Advantageous therapeutic embodiments would therefore comprise BPI functional domain peptides having one or more than one of the activities of BPI.
This invention provides small, readily-produced peptides having an amino acid sequence that is the amino acid sequence of a BPI functional domain or a subsequence thereof and variants of the sequence or subsequence having at least one of the biological activities of BPI, such as heparin binding, heparin neutralization, LPS binding, LPS neutralization or bactericidal activity. The functional domains of BPI discovered and described herein include: domain I, encompassing the amino acid sequence of BPI from about amino acid 17 to about amino acid 45; domain II, encompassing the amino acid sequence of BPI from about amino acid 65 to about amino acid 99; and domain III, encompassing the amino acid sequence of BPI from about amino acid 142 to about amino acid 169. Thus, the BPI functional domain peptides are based on the amino-terminal portion of human BPI.
The peptides of the invention include linear and cyclized peptides, and peptides that are linear, cyclized and branched-chain combinations of particular BPI functional domain amino acid sequences or subsequences thereof and variants of the sequence or subsequence. Combination peptides include peptides having the sequence or subsequence and variants of the sequence or subsequence of the same or different functional domains of BPI that are covalently linked together. Specifically included are combinations from two to about 10 peptides of any particular sequence or subsequence thereof and variants of that sequence or subsequence. The invention also provides peptides having additional biological activities distinct from the known biological activities of BPI, including but not limited to bactericidal activity having an altered target cell species specificity. Peptides having particular biological properties of BPI that are enhanced or decreased compared with the biological properties of BPI are also provided.
The peptides of the invention include linear and cyclized peptides, and peptides that are linear, cyclized and branched-chain amino acid substitution and additional variants of particular BPI functional domain amino acid sequences or subsequences thereof. For the substitution variants, amino acid residues at one or more positions in each of the peptides are replaced with a different amino acid residue (including atypical amino acid residues) from that found in the corresponding position of the BPI functional domain from which the specific peptide is derived. For the addition variants, peptides may include up to about a total of 10 additional amino acids, covalently linked to either the amino-terminal or carboxyl-terminal extent, or both, of the BPI functional domain peptides herein described. Such additional amino acids may duplicate amino acids in BPI contiguous to a functional domain or may be unrelated to BPI amino acid sequences and may include atypical amino acids. Linear, cyclized, and branched-chain combination embodiments of the amino acid substitution and addition variant peptides are also provided as peptides of the invention, as are cyclized embodiments of each of the aforementioned BPI functional domain peptides. In addition, peptides of the invention may be provided as fusion proteins with other functional targeting agents, such as immunoglobulin fragments. Addition variants include derivatives and modifications of amino acid side chain chemical groups such as amines, carboxylic acids, alkyl and phenyl groups.
The invention provides pharmaceutical compositions for use in treating mammals for neutralizing endotoxin, killing Gram-negative and Gram-positive bacteria and fungi, neutralizing the anti-coagulant properties of heparin, inhibiting angiogenesis, inhibiting tumor and endothelial cell proliferation, and treating chronic inflammatory disease states. The pharmaceutical compositions comprise unit dosages of the BPI peptides of this invention in solid, semi-solid and liquid dosage forms such as tablet pills, powder, liquid solution or suspensions and injectable and infusible solutions.
This invention provides peptides having an amino acid sequence which is the amino acid sequence of human BPI from about position 17 to about position 45 comprising functional domain I, having the sequence:
Domain I ASQQGTAALQKELKRIKIPDYSDSFKIKH (SEQ ID NO:1);
and subsequences thereof which have biological activity, including but not limited to one or more of the activities of BPI, for example, bactericidal activity, LPS binding, LPS neutralization, heparin binding or heparin neutralization. Also provided in this aspect of the invention are peptides having substantially the same amino acid sequence of the functional domain I peptides having the amino acid sequence of BPI from about position 17 to about position 45 or subsequences thereof. Additionally, the invention provides peptides which contain two or more of the same or different domain I peptides or subsequence peptides covalently linked together.
This invention provides peptides having an amino acid sequence which is the amino acid sequence of human BPI from about position 65 to about position 99 comprising functional domain II, having the sequence:
Domain II SSQISMVPNVGLKFSISNANIKISGKWKAQKRFLK (SEQ ID NO:6);
and subsequences thereof which have biological activity, including but not limited to one or more of the activities of BPI, for example, bactericidal activity, LPS binding, LPS neutralization, heparin binding or heparin neutralization. Also provided in this aspect of the invention are peptides having substantially the same amino acid sequence of the functional domain II peptides having the amino acid sequence of BPI from about position 65 to about position 99 or subsequences thereof. Additionally, the invention provides peptides which contain two or more of the same or different domain II peptides or subsequence peptides covalently linked together.
The invention also provides peptides having an amino acid sequence which is the amino acid sequence of human BPI from about position 142 to about position 169 comprising functional domain III, having the sequence:
Domain III VHVHISKSKVGWLIQLFHKKIESALRNK (SEQ ID NO:12);
and subsequences thereof which have biological activity, including but not limited to one or more of the activities of BPI, for example, bactericidal activity, LPS binding, LPS neutralization, heparin binding or heparin neutralization. Also provided in this aspect of the invention are peptides having substantially the same amino acid sequence of the functional domain III peptides having the amino acid sequence of BPI from about position 142 to about position 169 or subsequences thereof. Additionally, the invention provides peptides which contain two or more of the same or different domain III peptides or subsequence peptides covalently lined together.
Also provided by this invention are interdomain combination peptides, wherein two or more peptides from different functional domains or subsequences and variants thereof are covalently linked together. Linear, cyclized and branched-chain embodiments of these interdomain combination peptides are provided.
The peptides of this invention have as one aspect of their utility at least one of the known activities of BPI, including LPS binding, LPS neutralization, heparin binding, heparin neutralization and bactericidal activity against Gram-negative bacteria. Additionally and surprisingly, some of the peptides of this invention have utility as bactericidal agents against Gram-positive bacteria. Another surprising and unexpected utility of some of the peptides of this invention is as fungicidal agents. Peptides of this invention provide a new class of antibiotic molecules with the dual properties of neutralizing endotoxin and killing the endotoxin-producing bacteria, useful in the treatment of mammals suffering from diseases or conditions caused by Gram-negative bacteria. Peptides of this invention that retain this dual activity and additionally have an increased antibiotic spectrum represent an additional new class of antimicrobial agents. In addition, peptides of the invention provide a class of antimicrobial agents useful in the treatment of infections by microbial strains that are resistant to traditional antibiotics but are sensitive to the permeability-increasing antimicrobial activity of peptides of the invention.
The invention also provides pharmaceutical compositions of the peptides of the invention comprising the peptides or combinations of the peptides in a pharmaceutically-acceptable carrier or diluent, both per se and for use in methods of treating pathological or disease states or for other appropriate therapeutic uses. Methods of using these pharmaceutical compositions for the treatment of pathological or disease states in a mammal, including humans, are also provided by the invention. Also provided by the invention are uses of BPI functional domain peptide for the manufacture of medicaments for a variety of therapeutic applications.
Specific preferred embodiments of the present invention will become evident from the following more detailed description of certain preferred embodiments and the claims.